77 lines
1.5 KiB
C
77 lines
1.5 KiB
C
/* Copyright (C) 2025 Aryadev Chavali
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the Unlicense for details.
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* You may distribute and modify this code under the terms of the Unlicense,
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* which you should have received a copy of along with this program. If not,
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* please go to <https://unlicense.org/>.
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* Created: 2025-08-19
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* Description: Pointer tagging
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*/
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#include <assert.h>
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#include <stdlib.h>
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#include "./alisp.h"
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lisp_t *tag_int(i64 i)
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{
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return TAG((u64)i, INT);
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}
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lisp_t *tag_sym(char *str)
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{
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return TAG((u64)str, SYM);
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}
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lisp_t *tag_vec(vec_t *vec)
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{
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return TAG((u64)vec, VEC);
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}
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lisp_t *tag_cons(cons_t *cons)
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{
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return TAG((u64)cons, CONS);
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}
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tag_t get_tag(lisp_t *lisp)
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{
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static_assert(NUM_TAGS == 5);
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if (!lisp)
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return TAG_NIL;
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else if (IS_TAG(lisp, INT))
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return TAG_INT;
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return (u64)lisp & 0xFF;
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}
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i64 as_int(lisp_t *obj)
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{
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assert(IS_TAG(obj, INT));
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u64 p_obj = (u64)obj;
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return UNTAG(p_obj, INT) | // Delete the tag
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(NTH_BYTE(p_obj, 7) & 0x80) << 56 // duplicate the MSB (preserve sign)
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;
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}
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char *as_sym(lisp_t *obj)
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{
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assert(IS_TAG(obj, SYM));
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return (char *)UNTAG(obj, SYM);
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}
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cons_t *as_cons(lisp_t *obj)
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{
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assert(IS_TAG(obj, CONS));
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return (cons_t *)UNTAG(obj, CONS);
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}
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vec_t *as_vec(lisp_t *obj)
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{
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assert(IS_TAG(obj, VEC));
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return (vec_t *)UNTAG(obj, VEC);
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}
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